Lighting fixture



Dec. 7, 1943.

B. A MITCHELL LIGHTING FIXTURE Filed Dec. 11, 1941 4 Sheets-Sheet l1943. B. A. MITCHELL I LIGHTING FIXTURE Filed Dec. 11, 1941 4Sheets-Sheet 2 A MN cffllvhzgy Dec. 7,1943. 5. MlTcHELL 7 2,336,414

LIGHTING FIXTURE Filed Dec. 11, 1941 4 Sheets-Sheet 3 FIE/.7

A fill/6212 01 Bernard J? 77?;50/2612 1943. B. A. MITCHELL 2,

- LIGHTING FIXTURE Filed Dec. 11, 1941 4 Sheets-Sheet 4 L 6 3 25 EggPatented Dec. 7, 1943 UNITED STATES PATENT OFFICE LIGHTING FIXTUREBernard A. Mitchell, Chicago, Ill. Application December 11, 1941 SerialNo..422, 491

8 Claims.

This invention relates to improvements in lighting fixtures and moreparticularly to fluorescent lighting fixtures.

One of the objects of my invention is to provide a standardized fixturewhich may be readily mounted either in pendant mounting, in-

dividual ceiling mounting or continuous row mounting, thus considerablyeliminating the paired and which has a high lighting efliciency with alow surface brightness.

Another object is to provide a fixture which is economical tomanufacture and to maintain in operating condition.

Other objects will become apparent as description progresses.

In the drawings Fig. l is a perspective view of my fixture.

Fig. 2 is a perspective view showing the manner of mounting theindividual fixture on a ceiling.

Fig. 3 is a perspective view showing the manner of mounting a pluralityof fixtures on a celling in a continuous row.

Fig. 4 is a cross sectional view taken on line 4-5 of Fig. l, butshowing the side panels in elevated position and the bottom panel partlyremoved.

Fig. 5 is a perspective view of the cover and the ' glass panelsupporting member.

Fig. 6 is a perspective view showing the appearance of a plurality offixtures when mounted in a ceiling in a continuous row.

Fig. '7 is a sectional view taken on line 3-7 of Fig. 4.

Fig. 8 is a perspective view showing the fixture mounted by a pendant.

Fig. 9 is a longitudinal cross sectional view of the structure shown inFig. 8.

Fig. 10 is a sectional view taken on line ill-l9 of Fig. 9.

Fig. 11 is a sectional view taken on line l|-Ii of Fig. 9.

Fig. 12 is a sectional view taken on line l2-|2 of Fig. 9.

Fig. 13 is a sectional view taken on line lS-li of Fig. 3.

The fixture indicated generally at 20 is formed of a pair of end members2|, alongitudinal tubular body'or housing 23, fluorescent lighting tubes24, and side and bottom glass panels 25 and 26 respectively.

The end members are identical in size and shape and have converging sideflanges 21, and horizontal top and bottom flanges 28 and 29respectively. The bottom flange 29 has upturned ends 29a. An opening 30is provided in each end member and permits and entrance into theinterior of the housing 23. This opening is covered by an ornamentaldisc 35, which is held in place by a threaded bolt 32 passing throughthe end members 2! and the socket'plates 33 hereinafter to be described.

The socket plate 33 is heldin place against the end member 2! by thebolt 32 when the fixtures are individually mounted. However when thedisc Si is removed for end to end mounting of the fixtures, as will morepresently be described, a flat head screw 22 (Fig. '7) is substituted.

The socket plate has an inwardly bent portion 34 underlying the flange28. A pair of bracket members 35 additionally secures said socket plateto said end member. The fluorescent tube sockets 36 are secured as bybolts and nuts 31 to the socket plate, and it will be seen that the- .onthe plate 33 under the portion 34 is a right angled member 6! whichcarries a clamping bolt 62 for a purpose more presently to be described.

The housing 23 is rectangular shaped in cross section and has secured toits opposite ends the socket plates 33,- which are secured by rivetspassing through the flanged ends 23a of the housing. Three knockouts areprovided on each side of the housing (only two 2% and 28c being shown)so that an outlet Moan be connected to said housing in any of said spotswhen the knockout. is removed. Two shown, are provided in the top of thehousing for use when the fixture is pendant mounted as shown in Figs. 8and 9. The housing is open along its bottom and is adapted to be closedby a flanged cover 40.

Secured to the cover 40 intermediately thereof knockouts not as byrivets, are a pair of substantially triangularly shaped supportingplates 4| having oppositely directed flanges 42. The plates are bent soas to be spaced from each other adjacent their upper portions, but arecontiguous along their lower portions. A channel bar 43 partiallyencloses the flanges 42 and serves to hold the plates together. Thechannel bar has upwardly bent end portions 43a.

The electrical units such as the starter sockets 64a, the starters 44,the ballast (not shown) and the wiring are all housed in the housing 23.The construction for supporting the starters and their sockets is bestseen in Figs. 9 and 10 and comprises a rectangularly shaped metal member45 provided with longitudinally flanged sides 45a and a central opening46. The sockets 44a are supported in pairs by a flanged clamp 41 securedby bolt and nut 56. The starter sockets 44a rest on the clamp while thestarter 44 extends through an opening 49 in the clamp. Replacement ofany starter may be easily efiected merely by withdrawing the starterfrom its socket. The plate 45 is secured from the top of the housing 23by means of bolts and is spaced-therefrom by sleeves 52 being secured bylock nuts 53. The bolts 5| are longer than the depth of the housing 23and extend through openings 54 in the cover 40 or the housing. Wing nuts55 serve to hold the cover 40 in place and thus enclose electricaloperating elements of the fixture. The cover 40 is also provided withopening 56 through which partially extend the starters 44. Removal ofthe cover 40 for access to the interior of the housing 23 may be easilyaffected by removal of the wing nuts 55.

The side glass panels 25 rest on the side flanges 21 of the end plates2| and are supported on the bottom flange 29. A pair of U shaped clips51 are secured to eachof the end plates 2| and are spaced with respectto the side flanges 21 so that the glass panel 25 normally will bepositioned between the wing 51a of the clip 51 and the flange 21 andwill be held in place against accidental displacement. Each of the twobottom glass panels 26 rest on the flanges 42 and 29 of the. centersupporting plate 4| and end member 2| respectively, accidental lateraldisplacement of the panels being prevented by upturned ends 43a and 29a.For maintenance of the fixture, particularly where the fixture ismounted directly to the ceiling, the side panel 25 is elevated slightlyand placed in the clip 51. This permits the bottom panels 26 to bewholly or partially withdrawn, as shown in Fig. 4, and permits access tothe interior of the fixture for repair, replacement or cleaning. Aplastic window 86 (Fig. 12) is mounted adjacent the inside of the endmember 2| and is held in place by 35 and a clip 19. When the fixturesare mounted end to end, the plastic windows are removed.

It it is desired to mount ing as an individual unit, shown in Fig. 2,are secured to the ceiling 59 by expansion or toggle bolts 60, with thetrackways 58a facing outwardly. The fixture is then positioned so thatthe flanges 28 of the end members 2| are slid onto the trackway 5811, asshown in Fig. 2, and rest thereon. when the fixture is properlypositioned, the clamping bolt 62 is tightened 'to engage the undersideof the trackway and to maintain the fixture against accidentally slidingof! said track. The flexible conduit 63 connected to a ceilingelectrical outlet is coupled to the outlet 64 on the housing 23 and itis through the lower portions of the brackets the fixture in the cell-.two ceiling tracks 66,

this conduit that the wire conductors are passed to the interior or thehousing 23.

To mount the same fixture in a continuous row mounting, as shown in Fig.6, I provide a ceiling supporting track which is a channel havingopposed inwardly directed trackways 66. 'This supporting track issecured to the ceiling by suitable expansion or toggle bolts, and isadapted to secure two adjacent end members 2|, clearly shown in Fig. 3.The supporting track 65 is first spacedly secured to the ceiling, wherethe two end members 2| would adjoin each other. In a continuous mountingthe single track 58 is also used to support the outermost end members2|. In mounting the fixture in a continuous row the disc 3| is firstremoved from all of the end members which will be positioned contiguousto other end members, thus exposing the openings 30 of each. The flathead screw 22 is substituted to hold the end member 2| and socket plate33 together. The fixture 20 is slid in the supporting track 65 with theflanged portions 28 and 34 resting on one of the trackways 66. Theadjoining fixture is also slid into the same trackway so that one endmember 2| thereof is contiguous to the end member of the adjoiningfixture and the trackway will support both end members end to end. -Whenproperly positioned the clamping bolt 621s tightened. When the endplates 2| are end to end, a bolt and nut 61 can be passed through thefilligre work to hold same together. The openings 36 communicating withthe interior of the housing will be in alignment with each other. Anipple 69 is then fitted into the openings 30 and 39 of each of the twoadjoining fixtures and serves to maintain the end members 2| inalignment (as well as their respective socket plates) and in additionprovides a, passageway through which the conductors or wires are passedfrom one fixture to another into the housing of each fixture as clearlyshown in Fig. '1. The nipple has a head 68a at one end and is locked inposition by a nut 66b. One or more unit fixtures may be easily removedwithout disturbing any or the others in the same series.

In connection with wiring the fixtures in an end to end'mounting, onlyone ceiling electrical outlet need be tapped and the fixture nearestsaid outlet can be connected by a flexible conduit 63 and coupled to thehousing outlet 64. It will be seen that though I have shown the housingoutlet 64 connected to the center of the housing 23, that forconvenience, the outlet can be secured to the other parts of the housingwhen the knockouts "band 260 are removed from the housing. Similarknockouts are provided on the opposite side of the housing. The wireconductors are then passed through said conduit to' the housing andthrough each of the housings of the series of fixtures and each or saidfixtures in the series is electrically connected with the source ofcurrent supply.

' the crowfoot 14 suitably anchored to the ceiling.

A canopy 15 held in place by bushings 16 encloses and hides from viewthe ceiling bracket fixture which may be used either for pendantmounting, individual ceiling mounting or continuous row mounting withoutrequiring any change of size, style or model of construction.

It is to be understood that the form of my invention, herewith shown anddescribed, is to be taken as a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may beresorted to, without departing from the spirit of my invention or thescope of the appended'claims- I claim:

1. In a fluorescent lighting fixture, said fixture comprising endmembers, a socket plate secured to each of said end members and spacedfrom said end members, said socket plate supporting a plurality ofsockets, a housing having its opposite ends secured to said socketplate, a plate supported within said housing by a plurality of bolts, aplurality of starters for said fixture clamped to said plate and readilyremovable therefrom, and a cover for said housing, said cover held incovered position by means fastened to said bolts.

2. In a fluorescent lighting fixture, said fixture including a pair ofend members, a socket plate secured to said end members, a housingsecured to said socket plate within which housing is contained theelectrical elements for operating said fixture, glass panels for thebottom and sides of said fixture resting on said end members, means onsaid end members for preventing'lateral displacement of said sidepanels, and means maintaining said side glass panels in elevatedposition to permit withdrawal of said bottom glass panel.

3. In a fluorescent lighting fixture, said fixture including a pair ofend members, a socket plate secured to said end members, a housingsecured to said socket plate within which housing is contained theelectrical elements for operating said fixture, said end wall and socketplate each having an opening communicatingwith the interior of thehousing, a readily removable disc for closing said openings, glasspanels for the bottom and sides of said fixture resting on said endmembers, and means on said end members for preventing lateraldisplacement of said side panels, said means maintaining said sidepanels in elevated position to permit withdrawal of said bottom glass.panel.

4. In a fluorescent fixture comprising a pair of end members, a bodymember between said end members within which is supported the electricaloperating elements for said fixture, a readily removable cover for saidbody member, glass panels for the sides and bottom of said fixture andclip members on said end members for maintaining said side glass panelsin elevated position to permit withdrawal of said bottom glass panel.

5. In a fluorescent fixture comprising a pair of end members, a bodymember between said end members within which is secured theelectrical'operating elements for said fixture, a supporting membersecured approximately midway of the length of said body member andadapted tosupport between it and the end members a pair of glass panelsforming the bottom of said fixture, a side glass panel for each of thesides of said fixture, and means on said end members for maintainingsaid side glass panels in elevated position to permit withdrawal of saidbottom panels. I

6. In combination with a trackway to be mounted on a ceiling, afluorescent lighting fixture comprising a pair of end plates, a housinghaving its ends secured to said end plates, a bottom panel, side panelssecured to said end plates, said side panels being movable to permitremoval of the bottom panel whereby to obtain access to the interior ofthe fixture, and means on the fixture slidable in said trackway tosupport the fixture from a ceiling.

7..,In a fluorescent lighting fixture comprising end plates, side andbottom supporting means adjacent the side and bottom edges of theendplates, a housing having its opposite ends secured to said end platesand supporting within it the electricaloperating elements for thefixture, a light transmitting bottom panel carried by the bottomsupporting means of the end 1 plates, light transmitting side panelssupported

